Method and apparatus for performing an open-end spinning operation

ABSTRACT

A method and apparatus for operating a yarn in an open end spinning system utilizing pneumatic suction force and a centrifugal force due to a high speed rotation of the spinning rotor at a time of stopping or restarting the spinning operation. Tension of the spinning yarn delivered from the rotor is detected. By positively insertion of the yarn into the rotor when a yarn tension below a predetermined value is detected, an upstream yarn end is maintained in the rotor without any contact with fibers accumulated upon the inside wall of the rotor during abnormal rotation of the rotor. The mentioned contact is revived when a normal rotation is recovered. Combination of a mechanical insertion mechanism with a pneumatic insertion mechanism assures further preferable result in the yarn piecing operation.

United States Patent Kom Susami Otsu-shl;

Masaakl Tabata, Otsu-shi; Masakazu Hirota, Saks-gun, Shiga-ken; Kelichi Minami, Otsu-shi; Teiryo Kojima, Otsu-shi,

[72] Inventors all 01, Japan [2]] Appl. No. 794,019

[22] Filed Jan. 27, 1969 [45] Patented Aug. 31, 1971 [73] Assignee Toray Industries, Inc. Tokyo, Japan [32] Priority Feb. 2, 1968, Feb. 26, 1968, Mar. 1, 1968,

Mar. 13, 1968, Mar. 29, 1968 [3 3 1 Japan and 43/201122 54] METHOD AND APPARATUS FOR PERFORMING AN OPEN-END SPINNING OPERATION 23 Claims, 20 Drawing Figs.

[52] 11.8. C1 57/5891, 57/5895, 57/80. 57/156 [51] 1nt.Cl. D01h1/12, D01h 13/16 [50] Field 01 Search 57/5889,

[56] References Cited UNlTED STATES PATENTS I 3,354,631 11/1967 Elias et a1. 57/58 95 3,462,936 8/1969 Boucek et a1. 57/80 3,492,804 2/1970 Landwehrkamp et a1. 57/5895 X Primary Examiner-John Petrakes Attorneys Robert E. Burns and Emmanuel J. Lobato ABSTRACT: A method and apparatus for operating a yarn in an open end spinning system utilizing pneumatic suction force and a centrifugal force due to a high speed rotation of the spinning rotor at a time of stopping or restarting the spinning operation. Tension of the spinning yarn delivered from the rotor is detected. By positively insertion of the yarn into the rotor when a yarn tension below a predetermined value is detected, an upstream yarn end is maintained in the rotor without any contact with fibers accumulated upon the inside wall of the rotor during abnormal rotation of the rotor. The mentioned contact is revived when a normal rotation is recovered. Combination ofa mechanical insertion mechanism with a pneumatic insertion mechanism assures further preferable result in the yarn piecing operation.

PATENTEU AUGB] l97i 3,601,969

sum 1 [1F 6 mmm m1 197: 3,601.; 969

SHEET 3 UF 6 PATENTEU was] 19m 7 3,601,969

SHEET 8 OF 6 UPSTREAM LENGTH OF YARN in mm ID 2b 30 4b YARN COUNTS ('s) INVENTOR.

METHOD AND APPARATUS FOR PERFORMING AN OPEN-END SPINNING OPERATION The present invention relates to a method for operating yarn of the open end spinning equipment and its apparatus, more particularly relates to a method and apparatus for piecing yarn and operating a yarn on a spinning equipment utilizing airflow and centrifugal force, at the time of yarn breakage and stopping or restarting of the equipment, respectively. Recently, so-called open end spinning equipment omitting a ring and a traveller has become the focus of attention in textile engineering, particularly one of the equipment utilizing air stream and centrifugal force is well known. In the open end spinning equipment utilizing air stream and centrifugal force, a bundle of fibers supplied from a given supply source is shredded into individual fibers separated from each other while carrying them by a high speed air stream and the individual fibers are transferred to a spinning rotor rotating at a very high speed so as to be accumulated on a inside peripheral wall of the rotor. Next, a layer of fibers accumulated on the inside peripheral wall of the rotor is continuously stripped therefrom and taken out from a central aperture formed through a bottom of the rotor while being twisted. However, the conventional open end spinning equipments are accompanied with many drawbacks to be solved for practical utilization thereof. That is, as the accumulated fibers are held cohering onto the inside peripheral wall of the high speed rotating rotor and the spinning speed of yarn is often of the conventional one, it is very much difficult to retrieving the yarn in case of yarn breakage. Therefore, a certain troubles disturbing the smooth spinning operation are made. Further, in case of applying the open end spinning, the package of yarn produced is always supplied to the weaving or knitting process without any rewinding operation and removing the yarn defects such as the piecing portion of the yarn. Therefore yarn defects contained in a final textile good causes lowering of the quality of the textile good.

When the spinning operation is stopped, the centrifugal force due to high speed rotation of the rotor is reduced and the connection of the producing yarn with the accumulated fibers is broken and the broken end of the yarn is dropped down from the central aperture of the rotor. So, it becomes impossible to connect the yarn end with the accumulated fibers at the time of restarting without inserting the broken end of the yarn into the rotor to contact with the accumulated fibers in the rotor.

An object of the present invention is to provide a method and apparatus for automatically retrieving the broken end of the yarn with the accumulated fibersof the rotating rotor on the open end spinning equipment without producing any yarn defects.

Another object of the present invention is to provide an easy and efficient method and apparatus for stopping or restarting the spinning operation of the open end spinning equipment, without dropping an end of the producing yarn from the rotor and any particular operation for piecing the yarn end with accumulated fibers in the rotor.

Other objects, characteristics and advantages of the invention will be apparent from the following description, claims and the accompanying drawings, in which,

FIG. I is a skeleton side view of an embodiment of the open end spinning equipment provided with an apparatus of the present invention,

FIGS. 2A, 2B and 2C are skeleton side views illustrating the function of a pneumatic device for supporting a broken end of the yarn at the time of restarting the spinning operation of the open end spinning equipment shown in FIG. 1,

FIGS. 2D, 2E and 2F are skeleton side views of another pneumatic device having the same function as the device shown in FIG. 2A,

FIG. 26 is a skeleton side view of the device shown in FIG. 2F at a time restarting of the spinning operation,

FIG. 3 is a skeleton side view of another embodiment of the open end spinning equipment provided with another apparatus of the present invention,

FIG. 4 is a perspective view of a main operating portion of the apparatus shown in FIG. 3,

FIG. 5 is a front view showing the main operating portion of the apparatus shown in FIG. 3,

FIG. 6 is a skeleton side view of a still other embodiment of the open end spinning equipment provided with a still another apparatus of the present invention,

FIG. 7 is a perspective view showing a device for shifting a yarn path into two directions alternatively,

FIG. 8A is a schematic side view of a device for measuring an upstream length of yarn which can be inserted straight into the spinning rotor,

FIG. 8B is an explanatory diagram showing the upstream length of yarn measured by the device shown in FIG. 8A in connection with the yarn count,

FIGS. 8C, 8D are schematic side views of mechanical means for inserting a yarn end into a spinning rotor of the open end spinning equipment according to the method of the present invention,

FIGS. 9, 10A and 10B are also schematic side views of another mechanical means for inserting a yarn end into a spinning rotor of the open end spinning equipment according to the method of the present invention.

Generally, in the open end spinning system utilizing a spinning rotor, a bundle of fibers supplied from a given supply source is once shredded into individual fibers separated from each other during their conveying from the given supply source to the rotor and the individual fibers are accumulated upon an inside peripheral wall of the spinning rotor in a stable condition by means of the centrifugal force due to high speed rotation of the rotor. Therefore, when the rotation of the spinning rotor is stopped, the centrifugal force caused by the high speed rotation of fibers around a central aperture formed through a bottom of the rotor is eliminated, the connection between the accumulated fibers with the bundle of fibers stripped from the inside wall of the rotor is broken, and the broken end of the producing yarn is dropped off from the central aperture of the rotor. Consequently, when the spinning rotor is again driven so as to restart the spinning operation, it is impossible to connect the broken end. of the yarn with the accumulated fibers in the rotor. Further, it is impossible to retrieve the yarn in a manner employable in case of the conventional spinning equipments. By our rnill tests, it was disclosed that the above-mentioned troubles can be solved by applying a method for inserting the broken end of the yarn through the central aperture into the spinning rotor so as to connect with the accumulated fibers in the rotor and then taking out the yarn from the central aperture of the rotor while twisting the yarn.

Further, as the inertia of delivery rollers of the supply source, spinning rotor, takeup roller are different from each other, it is impossible to stop them at the same instant or to maintain a constant rotating speed ratio between them. Consequently, for example, if the rotation of the spinning rotor is stopped after the stop of the running of another rotating elements, a certain excess number of twist is imparted to the yarn, in other words, irregular twisting of the yarn which causes the yarn breakage can not be avoided. On the other hand, under the situation contrary to the aforementioned, the twist density of the yarn becomes small, and irregular twisting of the yarn which causes the degradation of the yarn strength and therefore the yarn breakage can not be avoided. The same phenomenon occurs at the time of restarting the spinning operation. Therefore, in the present method, each unit operation such as supplying a bundle of fibers to the spinning rotor, driving or stopping the rotation of the spinning rotor, taking out the producing yarn etc. is operated with given time relations between them.

As is apparent from the foregoing discussions, a particular consideration on how to operate every element of the open end spinning equipment is required in order to provide a practically usable open end spinning equipment.

Several embodiments of the method and apparatus of the open end spinning equipment of the present invention are hereinafter illustrated in details with corresponding references to the accompanying drawings.

In the embodiment shown in FIG. 1, a bundle of fibers 2 is supplied successively and constantly through a pair of delivery rollers la and lb from a given supply source such as a drafting equipment into a fiber feeding device 3 in a finely oriented condition of the fiber arrangement in the bundle 2. A fluid stream of compressed air is supplied from an external air supply source 4 into the feeding device 3 through an electromagnetically controlled valve 5 in such a manner as to create a negative pressure within the feeding device 3. This compressed air is ejected onto the bundle of fibers 2 along a conveying direction of the bundle of fibers 2 through the feeding device 3. By the ejection of this compressed air, individual fibers in the bundle of fibers 2 are released from their mutually entangled condition and are conveyed downstream through a feeding pipe 6 together with the ejected air stream. Outlet end of the feeding pipe 6 is directed to an inside peripheral wall of a spinning rotor 8 which is pivotably supported by a delivery pipe 7 and rotated at a high speed. So, the air stream of containing fibers is ejected onto the inside peripheral wall of the spinning rotor 8, fibers are separated from the air on account of a centrifugal force due to a high speed rotation of the rotor 8 and successively accumulated on the peripheral wall while rotating around a rotating axis of the rotor 8 in a condition of cohering on the peripheral wall of the rotor 8. Thus accumulated layer of the fibers is next lengthwisely and successively stripped from the peripheral wall, taken out from the rotor 8 through the delivery pipe 7 so as to produce a spinning yarn 9 and the yarn 9 is taken up onto a package 19 by a pair of takeup rollers 10a and 10b. During this taking-out operation, the rebundled bundle of fibers is imparted twists by rolling along its lengthwise axis in contact with an inside wall of the rotor 8.

Supply of fibers to the spinning rotor 8 is started and/or stopped by detecting the value of the yarn tension by a tension detecting means comprising a limit-switch 12 located in between the rotor 8 and the takeup rollers 10a and 10b. The operation of the limit-switch 12 is so designed that it provides an output signal indicative of a defective spinning operation to stop the supply of the fibers in case the yarn tension is too small or nothing, while it starts the supply of the fibers in case the yarn tension exceeds a given value. The feeding device 3 is connected to the external air supply source 4 of the compressed air by way of the electromagnetic valve 5. Another terminal of the electromagnetic valve 5 is connected to the delivery pipe 7 by way of a compressed air supply box 11. This electromagnetic valve 5 shifts the path of the fluid stream of compressed air flowing therethrough in either direction toward the feeding device 3 or the air supply box 11 in accordance with the signal of the limit-switch 12. By this shift of the path of the compressed air, a fluid stream yarn tension is smaller than the given, compressed air is selectively supplied to the feeding device 3 or to the compressed air supply box 11, that is, the compressed air is supplied to the feeding device 3 in case the yarn tension reaches a given value while it is supplied to the supply box 11 in case the yarn tension is smaller than the given predetermined value or the yarn is broken. At a position just downstream of the delivery rollers la and 1b of the supply source, there is disposed a pneumatic suction nozzle 14 which is connected to a blower 15 by way of a duct 16 so as to always effect a' suction on the bundle of fibers 2. Therefore. in case supplyof the compressed air to the feeding device 3 is stopped on account of yarn breakage or stop of the equipment. the bundle of fibers 2 supplied through the delivery rollers la and'lb is sucked into the suction nozzle 14. The takeup rollers 10a and 10b and a winding roller 20 are so designed as to rotate into similar direction and the length of their reverse rotation is set by a timer as desired.

Next, the procedure of how to stop the open end spinning equipment having the aforementioned mechanism is hereinafter explained.

In this embodiment, simultaneously with stopping the rotation of the takeup rollers 10a, 10b and the winding roller 20,

positive driving of the rotor 8 is stopped, thereby the yarn tension is reduced. This lowering of the yarn tension is detected by the limit-switch 12, which stops supply of the fibers into the rotor 8 and actuates supply of the compressed air to the comvpressed air supply box 11. About this moment, the inertial equipment is stopped and the supply of the compressed air into the delivery pipe 7 is completely ceased under this situation the mentioned upstream yarn end of the spinning yarn falls down completely out of the rotor 8 and the delivery pipe 7, and it becomes impossible to reintroduce the yarn end into the rotor 8 at the time of restarting. In order to avoid such a mentioned trouble, the takeup rollers 10a, 10b and the winding roller 20 are reversely rotated for a predetermined degree prior to stopping of the supply of the compressed air into the delivery pipe 7 and finally stop the supply of the compressed air into the delivery pipe 7. By this reverse rotation of the rollers 10a, 10b and 20, the broken or separated end portion of the spinning yarn is inserted into the rotor 8. By suitably selecting the degree of the reverse rotation of the rollers 10a, 10b and 20, a sufficient length of the end portion of the spinning yarn is placed within the rotor 8 and the mentioned upstream end of the broken yarn does not fall down out of rotor 8 even after the whole equipment is stopped.

Although supply of the fluid stream of compressed air into the supply box 11 is utilized for keeping the broken yarn and at a preferably position in the present embodiment, this can also be positively realized by utilizing a suitable mechanical means such as a pair of nip rollers or nip belts disposed adjacent to the outlet of the delivery pipe 7. The constructions and features of such mechanical means will be introduced in details in the later discussion. The inserted yarn end is maintained at a position near the delivery pipe 7 within the rotor 8 and does not fall down further.

Restarting of the equipment can be carried out principally in a manner opposite to the above-mentioned. It the first place, supply of the compressed air into the delivery pipe 7 is revived. Next, the spinning yarn 9 is taken up slightly by the rollers 10a, 10b and 20 so as to lead the upstream portion of the yarn into the delivery pipe 7 for preventing the additional twists imparting to the upstream end of the yarn positioned within the rotor, the rotation of the rotor 8 is revived up to a normal rotating speed and the rollers 10a, 10b and 20 are rotated reversely after the rotation of the rotation 8 has reached a normal speed. As soon as the upstream yarn end contacts with the inside peripheral wall of the rotor 8, the revived yam tension is detected by the limit-switch 12 located just downstream of the outlet of the delivery pipe 7. Thus detected signal is transmitted to the valve 5, which effects the stop of the supply of the compressed air to the delivery pipe 7 and revival of the supply of the compressed air to the feeding device 3. Now, the supply of the fibers into the rotor 8 is revived and the rollers 10a, 10b and 20 again begin to take up the spinning yarn and all of the running condition of the equip ment becomes normal.

As is aforementioned, application of the present method of the invention to the actual open end spinning system assures automatic yarn retrieving operation without employing a particular yam piecing operation usually required at the time of restarting of the equipment. This high efficiency is actual operation is further accompanied with relatively simple mechanical construction of the apparatus of the present invention.

In case of the yarn breakage during normal running of the equipment, the broken yarn end is inserted or introduced back into the spinning rotor 9 by a fluid stream flowing toward the rotor 8 from the supply box Ill and is connected to a layer of fibers accumulated on the peripheral wall of the rotor 8. After completion of this connection, the yarn 9 is taken up by the takeup rollers 10a, 10b as usual and the automatic yarn retrieving is completed.

It is disclosed that complete and successful elimination of undesirable yarn breakage at the time of the starting of the open end spinning equipment can be realized by cancelling connection of the upstream yarn end with the peripheral wall of the rotor when the rotating speed of the rotor 8 is smaller than a definite value and reviving the mentioned connection when the rotating speed reaches the value. This is because rebundling of fibers in the open end spinning system is dependent upon the centrifugal force due to a high speed rotation of the rotor 9 and a normal rebundling of the fiber, that is a normal spinning condition, can not be expected if the rotation of the rotor is slower than the definite speed.

Further detailed mechanical function of the compressed air supply box I ll used in the equipment shown in FIG. 11 is shown in FIGS. 2A to 2C. In the condition shown in FIG. 2A, the rotor 8 is stopped or running at a speed not enough to bring about a normal spinning condition. That is, the rotor 8 is going to start or going ro increase its rotating speed in order to begin a normal spinning operation. There is neither the supply of fibers from the feeding pipe 6 to the rotor 9 nor positive introduction of the airstream from the feeding pipe 6 to the rotor 8. The upstream end of the yarn 9 is maintained within the spinning rotor 9 being blown by the compressed airstream ejected from the supply box 1111 and there is no connection between the end of the yarn 9 and the peripheral wall of the rotor 8 at this moment. If the rotation of the rotor 9 is revived and further increased in this situation, no twists can be imparted to the yarn 9 in the rotor 9. This is because of the fact that impartation of twists to the yarn 9 can be realized only by the presence of a connection of the upstream yarn end with fibers accumulated upon the inside peripheral wall of the rotor 8. 80, during the period before the rotor 9 has a rotating speed enough to carry out a normal spinning operation, the upstream end of the yarn 9 is maintained in a condition shown in FIG. 2A. FIG. 2B illustrates the condition of the yarn 9 and fibers in the rotor 8 at the moment when the rotating speed of the rotor 8 has become large enough to perform a normal spinning operation.

By increasing the rotating speed of the rotor 9, the yarn tension is increased and when the yarn tension reaches a predetermined value, the limit-switch l2 actuates to stop the supply of the compressed air from the supply box. 1 ll. Together with this, the supply of the air stream for conveying the airstream are revived and the airstream introduced into the rotor 8 blows the upstream end of the yarn 9 towards the peripheral wall of the rotor 8. Contact of the end of the yarn 9 creates connection of the yarn 9 with the layer of fibers on the peripheral wall of the rotor 9 and this results in normal impartation of twists to theyam 9. As soon as the mentioned connection is revived, the rollers Ma, 1191) and 2t) begin to rotate so as to take up the spinning yarn 9 onto the package 19. In FIG. 2C, an internal situation of the rotor 9 during thus revived normal spinning operation is shown.

Now the explanation is hereinafter made how to stop the normal running of the open-end spinning equipment of the present invention.

This can be performed in a manner opposite to the process of starting the equipment. That is, firstly the supply of air and the fibers from the feeding pipe 6 is stopped together with running of the rollers lltla, lltlb and 29. Simultaneously with this, a compressed air is ejected from the supply box 1111 towards the rotor. 9 so as to cancel the contact between the yarn 9 and the peripheral wall of the rotor. Next, rotation of 1 the rotor 8 is stopped. In the aforementioned process, all the steps can be carried out simultaneously too.

As is already described, yarn breakages at the time of starting or stopping the open-end spinning equipment, which was an indispensable drawback of the prior arts, can be effectively prevented by the employment of the method and apparatus of the present invention, wherein contact between the spinning yarn and the inside peripheral wall of a spinning rotor is cancelled during the period before the rotating speed of the spinning rotor is lower than the predetermined value.

There are several methods for cancelling the mentioned contact beside the one already illustrated. One of the examples is shown in FIG. 2D.

For example, an air suction tube Zll is disposed to an upper end of the rotor 9. During the period when the rotation of the rotor 8 is not fast enough to perform a normal spinning operation, the suction tube 21 works to hold the upstream end of the yarn 9 by sucking it and the contact of the yarn 9 with the peripheral wall of the rotor ti is cancelled. In the example shown in FIG. 2E, a combined operation of the compressed air supply box Ill and the air suction tube 21 is utilized for holding the yarn end. In case of the example shown in FIG. 2F, a yarn end holding tube 22 is disposed to the bottom aperture of the rotor 8 and the holding tube 22 is connected to an air supply box ll 1. During the period when the rotor 8 is provided with an insufficient rotation, the holding tube 22 is located within the rotor 8 and the air supply box 111 is put in an operating condition so as to completely cancel the contact of the yarn 9 with the peripheral wall of the rotor 9. In FIG. 2G, a normal spinning condition of the example shown in FIG. 2F is shown. In this condition, the rotating speed of the rotor 9 is supposed to be large enough to bring about the normal spinning operation and the spinning yarn 9 is apparently con nected with layer of fibers on the peripheral wall of the rotor 8. As is apparently shown in the drawings, the holding tube 22 is downstream receded from inside the rotor 9, so as to enable normal spinning operation, under this situation. In case of the illustrated examples, the compressed air is ejected only into a single direction from the supply box 11. However, it can be ejected into several directions too. It is further preferably to eject the compressed air in a manner to create a vortical air stream within the delivery pipe 7. The air suction tube 211 is not necessarily required to be disposed to the rotor 9 coaxially therewith. Any type of mechanical arrangement can be employed in this connection so far as it can cancel the contact of the yarn 9 with the peripheral wall of the rotor 8 by its sucking operation. If the air suction tube 211 is arranged in such a manner that it creates a vortical air flow within the rotor 8, the result will be far better with the possibility of stable spinning condition.

Another embodiment of the method and apparatus of the present invention is shown in FIGS. 3 and l. In case of the present embodiment, the pneumatic means of the foregoing embodiment for insertion of the yarn end into the rotor is accompanied with a mechanical means for carrying out the same. The mechanical arrangements and operations of the spinning rotor 8 and its related parts of the equipment are supposed to be the same with those of the first embodiment shown in FIG. 1.

In FIG 3 the limit-switch 12 having a tension detecting wire 13 is related to an electromagnetic valve 29 connected to a compressed air supply source (not shown). When the spinning yarn 9 is processed in a normal condition, the yarn tension effects the limitswitch 112 to close the circuit and the compressed air is supplied to the fiber feeding device 3. When the equipment ceases its normal running, the limit-switch 112 effects the supply of the compressed air to a jet device 25. This jet device 25 supplies compressed air into the rotor 9 so as to hold the broken yarn end at a certain position in the rotor 8 as already mentioned. Of course, this supply of the compressed air by the jet device 25 may be brought about not only at the time of the stop of the equipment but also during normal running condition thereof. Purpose of the provision of the pneumatic suction nozzle M and the blower 15 is the same with that of the preceding embodiment. A pair of nip rollers 26a, 26b are disposed in between the detecting wire 13 and the takeup rollers a, 10b. Rotating direction of the nip roller 26a, 26b is opposite to that of the takeup rollers 10a, 10b and, for this reason, their nip points of the yarn is positionally differed from each other. A guide lever 27 operated by a solenoid 28 is located in between the nip rollers 26a, 26b and the takeup rollers 10a, 10b. This guide lever 27 selectively defines the path of the yarn 9 through the rollers 26a, 26b, 10a and 10b in accordance with signals transmitted from the limitswitch 12. During normal spinning operation, the guide lever 27 entrust the yarn 9 to the nip by the takeup rollers 10a, 10b and the yarn 9 is positively taken up onto the package 119. In case of restarting the equipment, the yarn 9 is transferred from the nip by the takeup rollers 10a, 10b to the nip of the nip rollers 26a, 26b by the shifting operation of the guide lever 27 and the yarn is inserted upstream into the rotor 8 by the mentioned reverse rotation of the nip rollers 26a, 26b. Further, a solenoid 30 is disposed adjacent to the package 19 so as to selectively effect the taking-up operation of the yarn 9 onto the package 19 according to the signals transmitted from the limit-switch 12.

In the arrangement shown in FIG. 4, both of the nip rollers 26a, 26b and the takeup rollers 10a, 10b are supported at their one ends. In the arrangement shown in the drawing, the driving mechanisms of, for example, the takeup roller 10b and the nip roller 26b is disposed independently form the other elements and they can be engaged with the other elements, for instance, by a clutch mechanism whenever desired.

The operations of the yarn and the related parts of the equipment at the time of restarting of the equipment of the present invention is hereinafter explained in details.

In the first place, the delivery rollers Ia, 1b of the supply source and the rotor 8 are actuated by pushing a starting switch of the equipment. Restarting of the rotor 8 usually requires a relatively long time because the rotor is run in most cases at a rotating speed up to ten thousands of revolutions per minutes. In this case, the upstream length of the yarn is too short to rotate by the rotation of the rotor 8 and such a lowspeed rotation of the upstream end of yarn does not provide the yarn tension sufficient to actuate the limit-switch 12. So, the supply of the compressed air into the fiber feeding device 3 is not yet actuated and the fiber feeding operation to the rotor 8 is not yet started. The bundle of fibers 2 is still conducted into the blower through through the nozzle 14. At the moment when the rotation of the rotor 8 reaches the normal rotating condition, all of the system recovers their normal running condition. This restarting of the running of the system can be carried out both manually and automatically, that is, for example utilizing a timer or an electromagnetic clutch mechanism. By this restarting of all of the system, the upstream portion of the spinning yarn 9 is inserted into the rotor 8 by the reverse rotation of the nip rollers 26a, 26b, rotation of the yarn end around the rotating axis of the rotor 8 begins to take place and the tension of the spinning yarn 9 is revived.

The upstream length of the spinning yarn 9 differs from spindle to spindle and varies depending upon the lengths of the broken yarn ends remaining in the respective spinning rotors 8. However this variation in the upstream length of the spinning yarn 9 can be compensated at the moment when the yarn tensions of the spindles reach a definite value. Finally, the yarns 9 are taken out from the respective rotors 8 and taken up onto the respective packages 19 by the combined operation of the tension detecting wires 13, guide levers 27 and the takeup rollers 10a, 10b in order to complete the restarting operation of the equipment. In other words, in case of the present embodiment, a normal spinning operation of the spindles can be started only when the difference in the yarn tensions among spindles becomes neglected. Thus the variation of the spinning condition among the spinning condition among the spindles can effectively be minimized by the application of the method and apparatus of the present invention resulting in a production of spinning yarns having desirable and favorable retrieved portions.

As is apparent from the foregoing discussions, an effective production of a spinning yarn having desirable and preferable piecing portion can be. realized by reviving the running of the fiber supplying means and the yarn taking up means after the completion of the normal running of the spinning rotor.

Furthermore, in the present embodiment, the aforementioned restarting of the equipment is realized after broken yarn ends of the respective spindles are taken up to positions wherein no rotation of the yarn ends within the rotors is effected.

Referring to FIG. 5, generally, most of the yarn breakages in the conventional open-end spinning systems are caused by the troubles in the twisting of the yarn and they take place at a position where the twisting of the rebundled bundle of fibers starts, that is the largest diametrical portion of the inside peripheral portion of the spinning rotor 8. Supposing that the breakage of the yarn takes place at a position (a) which corresponds to the largest diametrical portion of the peripheral wall of the rotor 8, the breaking point a is gradually advanced to a point 2 adjacent to the bottom aperture of the rotor 8 because of the successive taking up of the spinning yarn 9 by the takeup rollers 10a, 10b. At the point of a, no rotation of the yarn end takes place and the yarn tension due to the centrifugal force provided by the self-rotation of the yarn is disappeared. Then, the next moment, the detecting wire 13 shifts its position rightwards in FIG. 4, and the following operations are carried out,

1. the limit-switch 12 opens the circuit,

2. the magnet valve 29 stops the supply of the compressed to the feeding device 3 (this means the stop of the fiber supply) and the supply of the compressed air into the jet device is revived,

. the guide lever 27 shifts its position from d to d in FIG. 5

by the operation of the solenoid 28,

4. contact of the winding roller 20 with the package 19 is released by the cancellation of the sucking force of the solenoid 30 so as to stop the takeup operation of the spinning yarn 9 onto the package 19 and the behavior of the yarn is as follows.

5. On account of the shift of the position of the guide lever 27 located upstream of the takeup roller 10a, 10b, the yarn 9 is released from the nip point by the takeup rollers 10a, 10b and the taking-up operation on the yarn 9 is can celled.

. Further shift of the position of the guide lever 27 brings the yarn 9 to the nip point by the nip rollers 26a, 26b and the yarn 9 is carried toward the rotor 8 by the reverse rotation of the nip rollers 26a, 26b.

7. During the foregoing procedure, the contact of the winding roller 20 with the package 19 is kept cancelled and the yarn 9 is rewound from the package by the tension of the yarn 9 itself caused by the reverse rotation of the nip rollers 26a, 26b. Thus the broken point a is returned to its original position a on account of the combined operation of the nip rollers 26a, 26b with the jet device 25 and is provided with a tension due to the self-rotation thereof around the rotating axis of the rotor 8. The yarn tension thus revived returns the tension detecting wire 13 to the position 0 and thus the limit-switch l2 closes the circuit. Then,

8. the supply of the compressed air to the jet device 25 is stopped to revive the supply of the fibers to the rotor 8,

9. the guidelever 27 returns from the position d to the position :1 being controlled by the solenoid 28 and it transfers the yarn 9 from the nip by the nip rollers 26a, 26b to the nip by the takeup rollers 10a, 10b.

10. Simultaneously with this, the winding roller 20 comes in contact with the package 19 to take up the yarn onto the package 19. Needless to say, the broken point of the yarn is already connected with the layer of fibers accumulated on the peripheral wall of the rotor at this moment and the twisting operation of the yarn by the equipment can be carried out in a normal condition. Therefore, even at the time of the aforementioned accidental yarn breakage, retrieving of the yarn can be carried out instantly and automatically without any trouble.

A still other embodiment of the method and apparatus of the present invention is shown in FIG. 6. All of the elements of the equipment but the following takeup mechanism and dancer arm are arranged in a manner same with that of the foregoing embodiments.

In the embodiment, the braking magnetic clutch 31 operates to stop the taking-up operation when the limit-switch I2 opens the circuit. Simultaneously with this, the nip rollers 26a, 26b come into a position to carry the yarn 9 into the rotor 8 in a manner already explained. The length of the yarn 9 to be carried into the rotor 8 is controlled by the counterclockwise turning of a dancer arm 33 pivotally supported by a bearing 32 secured to the frame of the equipment. Another end of the dancer arm 33 is engaged with a switch 34 in such a manner that the switch 3 1 is effected when the dancer arm 33 is turned more than a predetermined angle. The switch 34 is usually maintained so as to connect P and Q terminals. However, excessive turning of the dancer am 33 cancels this connection and produces a new connection between R and Q terminals and this always keeps the guide wire 27 in a position to lead I the yarn 9 to the nip point by the takeup rollers a, 10b.

By employing the aforementioned arrangement, creation of the irregular yarn tension due to inertial rotation of the package at the time of rewinding and the time lag caused by it can effectively be prevented. Furthermore, because the length of the yarn to be carried into the rotor by the operation of the switch is limited, so-called hunting treatments of the yarn at the time of yarn retrieving can also be prevented.

Referring to FIG. 7, another embodiment of the nip rollers is illustrated. In this embodiment, a nip roller 35 is rotated into a definite direction (into clockwise direction in case of the ar-' rangement in the drawing) and is accompanied with a pair of auxiliary rollers 36, 37 under a pressure contact. The auxiliary rollers 36, 37 are peripherally covered with rubber layers. Sandwiching the rollers 35, 36, 37, a pair of yarn guide disks 38a, 390 are locatedialong the yarn path. The guide disks are provided with respective cutoffs for guiding the yarn formed on their peripheries and are pivotally supported by shafts 38b, 39b. Rotation of the guide disks 38a, 39a is actuated by a certain external driving source (not shown) related thereto. By a suitable turning of the disks 3&0, 39a, the passing yarn 9 can be selectively transferred from a nip by the rollers 35, 36 to a nip by the rollers 35, 37 and vice versa.

In most of the foregoing embodiments, a stream of a compressed air is utilized for carrying the broken yarn end into the spinning rotor. However, repeated tests by the inventors of the present invention have made it clear that the mentioned purpose can also be realized by utilizing only mechanical means without employing the mentioned pneumatic means. One of the examples is shown in FIGS. 8A and 8B. In FIG. 8A, when the length of the yarn carried upward by the nip rollers 43a, 43b through the yarn guide 40 is short, the yarn is maintained in its attitude in a condition designated as 42a. When the mentioned length reaches to a certain limit, the yarn buckles down into a condition designated as 42!: on account of its own weight. This limit length of the yarn maintained its straight condition is called as upstream length and is measured using a scale -lll disposed along the yarn path. In FIG. 8B, relations between the upstream length and the count of the yarn are graphically shown with plots. In this test, the specimen yarn is supposed to be manufactured on an open end spinning equipment shown in FIG. I. It is apparent that the finer the yarn, the shorter the upstream length of the yarn and that the upstream length of the yarn does not go below 10 mm. Therefore, in case no pneumatic means for carrying the yarn end into the rotor is employed in the system,the distance between the outlet terminal of the delivery pipe 7 and the nip point of the nip rollers 43a, 43b should preferably be smaller than 10 mm. Internal diameter of the delivery pipe 7 should be so designed as to permit a smooth introduction and passing of the upstream yarn without formation of fluffs. In order to ensure this smooth introduction of the upstream yarn, the outlet terminal of the delivery pipe should preferably be converged downwardly as shown in FIG. 8D. Further preferable nipping effect on the yarn can be brought about by employing a pair of apron rollers 44a, 44b as shown in FIG. 9 or two pairs of nip rollers 45a, 45b, 46a, 46b as shown in FIGS. 10A and 108. Both of the modifications are suitable for straightly introducing the upstream yarn into the rotor 18 through the pipe 7 without any trouble. In case of using only mechanical means for carrying the broken yarn end into the rotor, it is desirable to make the length of the delivery pipe 7 as short as possible and the internal diameter of the delivery pipe 7 as large as possible. The larger the thickness of the spinning yarn, the easier is the carrying operation of the yarn into the rotor of the present embodiment. The method of the present embodiment is particularly appreciated when it is used for carrying the upstream yarn of a larger thickness into the rotor because of a large quantity of pneumatic consumption is generally required for carrying such a yarn.

In the embodiment shown in FIG. 103, the upper nip rollers 45a, 4511 are kept in a detached relation during the normal spinning operation while they are brought into a pressure contact so as to carry the yarn into the spinning rotor 8 when the yarn breakage is detected. This shift in the mechanical relation is caused by signals transmitted from the limit-switch 12 in accordance with the detected yarn breakage. At this moment, the yarn is released from the nipping operation by the nip rollers 46a, 46b by the operation of the shifting means such as shown in FIGS. 3 and 4.

While the invention has been described in conjunction with certain embodiments thereof, it is to be understood that vari ous modifications and changes may be made without depart ing from the scope and spirit of the present invention.

We claim:

ll. An open end spinning method comprising: providing a fiber bundle of individually separated fibers; conveying said fiber bundle to an open-ended spinning zone; spinning said fibers in said open-ended spinning zone into a spun yarn and delivering the spun yarn under tension therefrom; continuously detecting the tension of the spun yarn and providing an output signal whenever the tension falls below a predetermined value indicative of a defective spinning operation; and automatically terminating the delivery of said fiber bundle to said open-ended spinning zone followed by fluidly introducing a portion of the spun yarn back into said open-ended spinning zone both in response to said output signal.

2. A method according to claim 1; wherein said conveying step comprises entraining said fiber bundle in a first fluid stream to convey same to said open-ended spinning zone; wherein said terminating step comprises rendering ineffective said first fluid stream in response to said output signal; and wherein said introducing step comprises entraining the spun yarn portion in a second fluid stream to introduce same back into said open-ended spinning zone in response to said output signal.

3. A method according to claim 2; including stopping said spinning step prior to said introducing step.

4. An open end spinning method comprising: pneumatically transporting a fiber bundle of individually liberated fibers to an open-ended spinning rotor having a delivery pipe connected to its downstream end; rotating said open-ended spinning rotor at a given speed to effect spinning of said fiber bundle into a twisted yarn accompanied by delivery thereof through said delivery pipe; taking up in one direction said twisted yarn delivered from said delivery pipe under tension; continuously detecting the tension of said twisted yarn passing through said delivery pipe and providing an output signal whenever the tension falls below a predetermined value indicative of a yarn separation from said. fiber bundle; and introducing the training end of the separated yarn through said delivery pipe back into said open-ended spinning rotor in response to said output signal.

5. A method according to claim 4; wherein said introducing step comprises, in the following sequence, simultaneously stopping both the transporting of said fiber bundle and the taking-up of said twisted yarn, stopping rotation of said openended spinning rotor, and providing a fluid stream effective to carry said trailing yarn end through said delivery pipe into said open-ended spinning rotor when said taking-up step is reversed, and reversing the direction of operation of said taking-up step, whereby said trailing yarn end is carried back into said open-ended spinning rotor.

6. A method according to claim 5; comprising after said reversing step, again rotating said open-ended spinning rotor to reunite said trailing yarn end with said fiber bundle, rendering ineffective said fluid stream when the tension of the reunited yarn is greater than said predetermined value, and then restarting both the transporting of said fiber bundle and the taking-up of said twisted yarn.

7. A method according to claim 6; wherein said restarting of the taking-up of said twisted yarn occurs after the rotational speed of said open-ended spinning rotor reaches said given speed.

8. A method according to claim 6, including maintaining said trailing yarn end in said spinning rotor by entraining same in said fluid stream without contacting an interior peripheral wall of said spinning rotor during an abnormal rotation of said spinning rotor and permitting said trailing yarn end to come into contact with fibers accumulated upon said interior peripheral wall of said spinning rotor when a normal rotation of said spinning rotor is reached.

9. A method according to claim 8, wherein said trailing yarn end is maintained within said delivery pipe during said abnormal rotation of said spinning rotor and is led into said spinning rotor by said fluid stream when said normal rotation of said spinning rotor is reached.

10. In combination: an open-ended, rotationally driven, spinning rotor receptive during operation of a fiber bundle of individually liberated fibers to spin the fiber bundle into a spun yarn and having a delivery pipe connected thereto through which the spun yarn is'delivered; supply means for supplying a fiber bundle of individually liberated fibers to said open-ended spinning rotor; detecting means disposed downstream from said delivery pipe for continuously detecting the tension of the spun yarn and providing an output signal whenever the yarn tension decreases below a predetermined value indicative of a yarn separation; interrupting means for interrupting the supplying of said fiber bundle to said openended spinning rotor in response to said output signal; and introducing means for fluidly introducing an end portion of the separated yarn back through said delivery pipe into said openended spinning rotor in response to said output signal.

11. A combination according to claim 10; wherein said supply means includes means for developing a first fluid stream entraining therein said fiber bundle; said introducing means comprises means for developing a second fluid stream flowing through said delivery pipe into said open-ended spinning rotor efTective to entrain therein said yarn end portion and introduce same back into said open-ended spinning rotor in response to said output signal.

12. A combination according to claim 11; wherein said interrupting means includes valve means operable in a first mode in the absence of said output signal to effect formation of said first fluid stream while preventing formation of said second fluid stream and a second mode in response to said output signal to eflect formation of said second fluid stream while preventing formation of said first fluid stream.

13. A combination according to claim 12, wherein said introducing means further comprises mechanical means for mechanically carrying said yarn end portion in an upstream direction toward said rotor simultaneously with the flowing of said second fluid stream, said mechanical positive means being disposed at a position downstream of said second fluid stream.

14. A combination according to claim 13, wherein said mechanical means is a pair of relatively movable nip rollers positioned in noncontact relationship during the normal spinning operation and movable into contact with each other in response to said output signal.

15. A combination according to claim 14, further comprising time-lag means attached to said mechanical means for starting contact movement of said nip rollers with a time-lag after said detecting means provides said output signal.

16. A combination according to claim 13, wherein said mechanical means comprises two pairs of rollers disposed in succession at positions below said second fluid stream, one of said pairs of rollers always contact each other and are rotating toward a takeup direction while the other pair of rollers always contact each other and are rotating toward the upstream direction which is reverse to said takeup direction, a guide lever operative to alternatively lead said yam to nip points of said pairs of rollers in accordance with said output signal of said detecting means, thereby when said detecting means detects yarn tension below a definite value, said guide lever leads said yarn to a nip point said pair of rollers rotating toward upstream direction and vice versa.

17. A combination according to claim 16, wherein said mechanical means further comprises means for changing the length of the spun yarn path of travel between said pairs of rollers and said taking-up means in response to said output signal.

18. A combination according to -claim 13, wherein said mechanical means comprises a rotating roller and a pair of auxiliary rollers contacting at symmetrical opposite positions of said rotating roller, means for alternatively leading said yarn to a nip point of one of said auxiliary rollers with said rotating roller or a nipt point of the other auxiliary rollers with said rotating roller in accordance with said output signal of said detecting means.

19. A combination according to claim 13, wherein said mechanical means is a pair of nip rollers whose direction of rotation is reversed in accordance with an output signal of said detecting means.

20. A combination according to claim 19, wherein the distance between said downstream terminal of said delivery pipe and a nip point of said nip rollers is not larger than 10 mm.

.21. A combination according to claim 13, wherein said mechanical means is a pair of nip apron belts whose rotating direction is reversed in accordance with an output control signal of said detecting means. I

22. A combination according to claim 12, including a yarn end holding tube slidably and coaxially disposed within said delivery pipe in such a manner that said yarn end holding tube projects into said spinning rotor during abnormal rotation of said spinning rotor while said tube recedes into said delivery pipe during normal rotation of said spinning rotor.

23. A combination according to claim 11, further comprising a source of suction, and an air suction tube connected to said source of suction and coaxially disposed to said spinning rotor to effect suction of said yarn end portion during abnormal rotation of said spinning rotor. 

1. An open end spinning method comprising: providing a fiber bundle of individually separated fibers; conveying said fiber bundle to an open-ended spinning zone; spinning said fibers in said open-ended spinning zone into a spun yarn and delivering the spun yarn under tension therefrom; continuously detecting the tension of the spun yarn and providing an output signal whenever the tension falls below a predetermined value indicative of a defective spinning operation; and automatically terminating the delivery of said fiber bundle to said open-ended spinning zone followed by fluidly introducing a portion of the spun yarn back into said open-ended spinning zone both in response to said output signal.
 2. A method according to claim 1; wherein said conveying step comprises entraining said fiber bundle in a first fluid stream to convey same to said open-ended spinning zone; wherein said terminating step comprises rendering ineffective said first fluid stream in response to said output signal; and wherein said introducing step comprises entraining the spun yarn portion in a second fluid stream to introduce same back into said open-ended spinning zone in response to said output signal.
 3. A method according to claim 2; including stopping said spinning step prior to said introducing step.
 4. An open end spinning method comprising: pneumatically transporting a fiber bundle of individually libeRated fibers to an open-ended spinning rotor having a delivery pipe connected to its downstream end; rotating said open-ended spinning rotor at a given speed to effect spinning of said fiber bundle into a twisted yarn accompanied by delivery thereof through said delivery pipe; taking up in one direction said twisted yarn delivered from said delivery pipe under tension; continuously detecting the tension of said twisted yarn passing through said delivery pipe and providing an output signal whenever the tension falls below a predetermined value indicative of a yarn separation from said fiber bundle; and introducing the training end of the separated yarn through said delivery pipe back into said open-ended spinning rotor in response to said output signal.
 5. A method according to claim 4; wherein said introducing step comprises, in the following sequence, simultaneously stopping both the transporting of said fiber bundle and the taking-up of said twisted yarn, stopping rotation of said open-ended spinning rotor, and providing a fluid stream effective to carry said trailing yarn end through said delivery pipe into said open-ended spinning rotor when said taking-up step is reversed, and reversing the direction of operation of said taking-up step, whereby said trailing yarn end is carried back into said open-ended spinning rotor.
 6. A method according to claim 5; comprising after said reversing step, again rotating said open-ended spinning rotor to reunite said trailing yarn end with said fiber bundle, rendering ineffective said fluid stream when the tension of the reunited yarn is greater than said predetermined value, and then restarting both the transporting of said fiber bundle and the taking-up of said twisted yarn.
 7. A method according to claim 6; wherein said restarting of the taking-up of said twisted yarn occurs after the rotational speed of said open-ended spinning rotor reaches said given speed.
 8. A method according to claim 6, including maintaining said trailing yarn end in said spinning rotor by entraining same in said fluid stream without contacting an interior peripheral wall of said spinning rotor during an abnormal rotation of said spinning rotor and permitting said trailing yarn end to come into contact with fibers accumulated upon said interior peripheral wall of said spinning rotor when a normal rotation of said spinning rotor is reached.
 9. A method according to claim 8, wherein said trailing yarn end is maintained within said delivery pipe during said abnormal rotation of said spinning rotor and is led into said spinning rotor by said fluid stream when said normal rotation of said spinning rotor is reached.
 10. In combination: an open-ended, rotationally driven, spinning rotor receptive during operation of a fiber bundle of individually liberated fibers to spin the fiber bundle into a spun yarn and having a delivery pipe connected thereto through which the spun yarn is delivered; supply means for supplying a fiber bundle of individually liberated fibers to said open-ended spinning rotor; detecting means disposed downstream from said delivery pipe for continuously detecting the tension of the spun yarn and providing an output signal whenever the yarn tension decreases below a predetermined value indicative of a yarn separation; interrupting means for interrupting the supplying of said fiber bundle to said open-ended spinning rotor in response to said output signal; and introducing means for fluidly introducing an end portion of the separated yarn back through said delivery pipe into said open-ended spinning rotor in response to said output signal.
 11. A combination according to claim 10; wherein said supply means includes means for developing a first fluid stream entraining therein said fiber bundle; said introducing means comprises means for developing a second fluid stream flowing through said delivery pipe into said open-ended spinning rotor effective to entrain therein said yarn end portion and introduce same back into said open-ended spinnIng rotor in response to said output signal.
 12. A combination according to claim 11; wherein said interrupting means includes valve means operable in a first mode in the absence of said output signal to effect formation of said first fluid stream while preventing formation of said second fluid stream and a second mode in response to said output signal to effect formation of said second fluid stream while preventing formation of said first fluid stream.
 13. A combination according to claim 12, wherein said introducing means further comprises mechanical means for mechanically carrying said yarn end portion in an upstream direction toward said rotor simultaneously with the flowing of said second fluid stream, said mechanical positive means being disposed at a position downstream of said second fluid stream.
 14. A combination according to claim 13, wherein said mechanical means is a pair of relatively movable nip rollers positioned in noncontact relationship during the normal spinning operation and movable into contact with each other in response to said output signal.
 15. A combination according to claim 14, further comprising time-lag means attached to said mechanical means for starting contact movement of said nip rollers with a time-lag after said detecting means provides said output signal.
 16. A combination according to claim 13, wherein said mechanical means comprises two pairs of rollers disposed in succession at positions below said second fluid stream, one of said pairs of rollers always contact each other and are rotating toward a takeup direction while the other pair of rollers always contact each other and are rotating toward the upstream direction which is reverse to said takeup direction, a guide lever operative to alternatively lead said yarn to nip points of said pairs of rollers in accordance with said output signal of said detecting means, thereby when said detecting means detects yarn tension below a definite value, said guide lever leads said yarn to a nip point said pair of rollers rotating toward upstream direction and vice versa.
 17. A combination according to claim 16, wherein said mechanical means further comprises means for changing the length of the spun yarn path of travel between said pairs of rollers and said taking-up means in response to said output signal.
 18. A combination according to claim 13, wherein said mechanical means comprises a rotating roller and a pair of auxiliary rollers contacting at symmetrical opposite positions of said rotating roller, means for alternatively leading said yarn to a nip point of one of said auxiliary rollers with said rotating roller or a nipt point of the other auxiliary rollers with said rotating roller in accordance with said output signal of said detecting means.
 19. A combination according to claim 13, wherein said mechanical means is a pair of nip rollers whose direction of rotation is reversed in accordance with an output signal of said detecting means.
 20. A combination according to claim 19, wherein the distance between said downstream terminal of said delivery pipe and a nip point of said nip rollers is not larger than 10 mm.
 21. A combination according to claim 13, wherein said mechanical means is a pair of nip apron belts whose rotating direction is reversed in accordance with an output control signal of said detecting means.
 22. A combination according to claim 12, including a yarn end holding tube slidably and coaxially disposed within said delivery pipe in such a manner that said yarn end holding tube projects into said spinning rotor during abnormal rotation of said spinning rotor while said tube recedes into said delivery pipe during normal rotation of said spinning rotor.
 23. A combination according to claim 11, further comprising a source of suction, and an air suction tube connected to said source of suction and coaxially disposed to said spinning rotor to effect suction of said yarn end portion during abnormal rotation of said spinning rotor. 